Anisotropic Elastic Full-waveform Inversion for a Real Walkaway VSP Data from The Arabian Gulf - Towards High Frequencies

Borehole vertical seismic profiling (VSP) data address the need for higher resolution images and information about shear wave velocities. Elastic full-waveform inversion (FWI) of VSP data provides promising capabilities to recover quantitative information about compressional and shear wave velocities for reservoir characterization. We apply elastic FWI to a walkaway data set from the Arabian Gulf and report on the results for medium frequencies (up to 40 Hz), which is at a resolution level of surface seismic data, and beyond (up to 60 Hz). The recovered model has a plausible layered structure and agrees fairly well with the sonic log data for both compressional and shear waves velocities in the vicinity of the well at the depth of the receivers antenna. Our FWI algorithm assumes axial symmetry for the VTI medium properties and can be applied for media with mild structural properties variations. The algorithm has a modest computational cost, comparable to the cost of 2D methods, yet it models true amplitude 3D point source solutions.